1. Field of the Invention
The present invention relates to an optical information recording medium for recording information on a recording film by irradiating a recording laser beam and to a manufacturing method thereof. The optical information recording medium includes an optical disk, an optical card and the like.
2. Description of the Related Art
A one-time write CD (compact disk) which is compatible with a normal CD in reproducing information is now commercialized as an optical information recording medium. It is formed by providing an organic pigment recording film, an Au reflecting film and an UV (ultraviolet) resin protecting film on a transparent plastic substrate. Signals are recorded thereon by selectively lowering reflectance of a recording section, which is caused by deformation of the substrate due to thermal decomposition of the organic pigment recording film caused when the recording laser beam is irradiated.
However, the conventional one-time write CD has a problem that because the organic pigment is applied on the transparent substrate by a spin-coater, the film-forming conditions vary depending on the ambient temperature and humidity of the spin-coater, thus lowering the production yield.
With respect to this problem, Japanese Patent Publication (JP-B-) No. Hei. 3-57540 discloses a recording medium in which an energy absorbing recording film is formed on a substrate by means of sputtering. A film in which a low melting point metal such as Te and In is combined with an element such as N and 0 is used as the energy absorbing recording film. When a laser beam is irradiated onto the recording film, gas generates from the inside of the recording film by spot heating. As a result, the raising deformation of the recording film is caused by the generated gas so that signals are recorded on the recording film.
Although the production yield improves since sputtering is used in manufacturing the optical information recording medium, no reflecting film nor protecting film can be coated on the recording film and no single-plate disk such as a CD can be formed because the raising deformation of the recording film is used to record signals. It is not also suited to signal recording according to a recording mark length modulating method because the length of a recording mark becomes inaccurate when the deformation of the film occurs.